Transient surface grating technique for thermal diffusivity measurement

Abstract

A new transient surface grating technique specifically designed for measuring thermal diffusivities of condensed materials is described. Its capabilities are illustrated with measurements of the thermal diffusivities of copper and glass.

Characterising Ion-Irradiated FeCr: Hardness, Thermal Diffusivity and Lattice Strain

“…For the thermal diffusivity of undamaged Fe10Cr, there is limited information in existing literature and comparisons were made with ASM217 alloy (8-10% Cr, 0.2% C and 1% Si) [55] and a Fe11.5Cr alloy (0.4% C and 0.3% Mn) [56], giving 15% and 25% agreement, respectively. TGS values of thermal diffusivity have been validated for a number of other material systems [20,38,57,58], which combined with the agreement with literature values for FeCr, gives confidence in our measurements.…”

Characterising Ion-Irradiated FeCr: Hardness, Thermal Diffusivity and Lattice Strain

“…Mn) [56], giving 15% and 25% agreement, respectively. TGS values of thermal diffusivity have been validated for a number of other material systems [21,38,57,58], which combined with the agreement with literature values for FeCr, gives confidence in our measurements. A trend of decreasing thermal diffusivity with increasing Cr content is observed.…”

Thermal Diffusivity of Film/Substrate Structures Characterized by Transient Thermal Grating Method

“…One of these methods is a transient thermal grating (TTG) method, in which two coherent pulsed laser beams are superposed with each other to produce an interference pattern on the surface of layered sample. [1−4] The laser energy with the interference fringes absorbed by an opaque or absorbing layer of the sample induces a periodic transient thermal gratings in the opaque or absorbing layer by the periodic temperature increase and thermal expansion, which can be observed by reflected diffraction experiments of a probe beam [1,2,4] or by reflected deflection effects of a well-focused probe beam from the corrugation of the deformation grating of opaque materials. [3] The former is always used to characterize thermal diffusivities and the latter is always used to evaluate mechanical or elastic properties of samples.…”

“…Generally U 0 (t) is very small, the first order diffraction intensity can be simplified to I 1 = I 0 (2πU 0 /λ) 2 . The diffraction efficiency η d (t) can be then expressed as…”